The U.S. Midwest is home to some of the nation's worst polluters -electric power plants. Some of these plants are old, and have never put in the newer control devices that would help limit their emissions. Perhaps one of the worst emissions is mercury. Now, in a move being watched by many US states, the Midwestern state of Wisconsin could become the first one in the country to force electric utilities to reduce the amount of mercury their plants put into the air.

Mercury is a major health concern for humans. If too much is ingested, it can cause severe neurological damage, especially in children. While much has been done to reduce mercury use in consumer products, little has been done to stop the biggest source of mercury - coal-fired power plants.

Much of the coal burned to produce electricity contains elemental mercury, and right now that mercury is simply released into the air when the coal is burned. The mercury eventually settles onto the land or the water. There, it makes its way into the food chain, and ultimately into humans.

The federal government doesn't currently restrict mercury emissions from power plants, but now Wisconsin is developing rules that would force utilities in the state to cut down. The state's Department of Natural Resources has proposed a plan by which power plants would reduce their emissions in three stages. The final limit would take place 15 years after the rule goes into effect, and would require a 90 percent emissions reduction. Utility companies are responding to the state, saying they can probably manage a 40 percent reduction.

Now, two committees are trying to hash out a compromise. They include representatives of environmental groups and utilities. Wisconsin Electric's spokesperson Kathleen Standen says her company is actively researching ways to control mercury emissions.

"Environmental objectives and regulations do force technology development, and we would rather be involved at the front end of technology development so that we can meet our own objectives at our own facilities," she said.

Ms. Standen and other utility executives are proposing an alternative to the state's plan. They want to design individual pollution reduction plans for each power plant. They say that would help them get the best economic and environmental return on their investment. Wisconsin Electric recently tested a system in which activated carbon is injected into the plant's exhaust. The mercury sticks to the carbon, and the carbon and mercury are removed from the exhaust together.

According to the company's tests, the system reduced mercury emissions by as much as 70 percent, but the new technology is not problem-free. Wisconsin Electric sells its ash to companies that use it to make cement. Adding the carbon changed the ash enough to make it impossible for the companies to use.

Lloyd Eagan oversees the mercury reduction plan for the Wisconsin DNR. She says the industry proposal for custom-designed limits on each plant might work. It could encourage companies to come up with solutions for several pollution problems at the same time. For example, there is a way to use activated carbon without ruining the ash, but that method would require the company to build an addition to the plant called a baghouse.

"If they were going to use one of those baghouses because they were going to do some other pollution controls, then it makes sense for them to put that investment in," she says. "And that's what makes this complicated is to try to look at this in terms of all the pollutants that they're trying to capture, and do it in a very cost-effective manner."

Scientists think roughly half the mercury in a plant's exhaust falls close to the plant, and the other half can be transported great distances. So power plants in Minnesota pollute lakes in Wisconsin, and Midwestern plants pollute New England waters. Utilities in Wisconsin say even if they clean up their emissions, Wisconsin lakes will still have too much mercury.

But environmentalists say it's still Wisconsin's responsibility to cut down on its mercury pollution. Russ Ruland is president of the Wisconsin Muskelunge Club, and he says the state's premiere sport fish, the musky, is having trouble reproducing - possibly because of mercury contamination.

"I don't see how we either as a state or as the United States can say, well, we're not going to do anything until somebody else does it," he says.

Meanwhile, the U.S. Environmental Protection Agency has been working for more than a year on rules to regulate mercury emissions from utilities nationwide. In March, the Bush administration announced its Clear Skies initiative. That would allow utilities to cut pollution at some plants but not others.

The Great Lakes Radio Consortium is a production of Michigan Radio. Support comes from the WK Kellogg Foundation, the Charles Stewart Mott Foundation, and the Gaylord and Dorothy Donnelley Foundation.